Excitotoxic Signaling in HD Transgenic Neurons

描述(由申请人提供)：亨廷顿病(HD)是一种 以选择性基底节为特征的遗传性神经退行性疾病 损伤和运动障碍。导致先天性巨结肠的基因缺陷是一种 亨廷顿蛋白中扩展的聚谷氨酰胺重复序列超过了这一点 在未受影响的个体中发现。扩展的机制 亨廷顿蛋白中的多谷氨酰胺重复导致神经元变性和运动 功能障碍是未知的。基于HD患者的研究结果和动物模型 有研究表明，遗传缺陷会导致新陈代谢受损。 从而增加了对谷氨酸诱导的神经元损伤的敏感性 (兴奋性毒性)。这种兴奋性毒性损伤可能与[Ca~(2+)]升高有关 线粒体功能障碍和氧化应激。最近，有几个转基因 表达突变亨廷顿蛋白基因的HD(HDTg)小鼠模型已被证实 产生并表现出类似于在 高清。来自该实验室和其他实验室的最新结果表明，HDTg小鼠确实如此 代谢酶活性有缺陷，神经元对 谷氨酸受体的激活在很大程度上是由 突变的亨廷顿蛋白。我们建议检验变种人的假设 亨廷顿蛋白表达导致线粒体功能障碍和亲离子 谷氨酸受体介导的神经毒性。这种谷氨酸能功能障碍可能 是神经元新陈代谢改变的结果或直接影响 亨廷顿蛋白突变表达引起的受体功能。作为高清的典范，我们 将在从HDTg培养的原代神经元中使用荧光成像技术 小鼠和它们的非转基因(WT)仔鼠来检验这一假设。我们的 具体目的是确定增强的机制(S) 1)谷氨酸受体介导的HDTg神经元的[Ca~(2+)]i反应。2) 谷氨酸受体刺激HDTg神经元线粒体去极化。3) HDTg神经元的兴奋性毒性神经元死亡。这些研究着眼于我们的长期 评估代谢折衷在谷氨酸毒性中的作用 与HD患者明显的神经元功能障碍和死亡有关。细胞培养 本工作中提出的HD模型也应提供一种方便的手段 测试HD的相关治疗方法。

DESCRIPTION (provided by the applicant): Huntington's disease (HD) is a hereditary neurodegenerative disease characterized by selective basal ganglia damage and movement disorders. The genetic defect responsible for HD is an expanded poly-glutamine repeat in the huntingtin protein in excess of that found in unaffected individuals. The mechanism by which the expanded poly-glutamine repeats in huntingtin causes neuronal degeneration and motor dysfunction is unknown. Based on findings in HD patients and animal models of HD it has been suggested that the genetic defect leads to metabolic compromise with consequent increased sensitivity to glutamate-induced neuronal injury (excitotoxicity). This excitotoxic injury may involve elevated levels of [Ca2+] mitochondrial dysfunction and oxidative stress. Recently, several transgenic mouse models of HD (HDTg) which express the mutant huntingtin gene have been created and exhibit neurologic symptoms and pathology similar to that seen in HD. Recent results from this laboratory and others suggest that HDTg mice do have deficits in metabolic enzyme activity and that neuronal responses to glutamate receptor activation are substantially altered by the expression of the mutant huntingtin protein. We propose to test the hypothesis that mutant huntingtin expression leads to mitochondrial dysfunction and ionotropic glutamate receptor mediated neurotoxicity. This glutamatergic dysfunction may be a consequence of alterations in neuronal metabolism or direct effects on receptor function caused by mutant huntingtin expression. As a model of HD, we will use fluorescence imaging techniques in primary neurons cultured from HDTg mice and their non-transgenic (WT) littermates to test this hypothesis. Our specific aims are to identify the mechanism(s) underlying the potentiation of 1) Glutamate-receptor mediated [Ca2]i responses in HDTg neurons. 2) Glutamate-receptor stimulated mitochondrial depolarization in HDTg neurons. 3) Excitotoxic neuronal death in HDTg neurons. These studies address our long-term goal of evaluating the role of metabolic compromise on glutamate toxicity as it relates to the neuronal dysfunction and death evident in HD. The cell culture models of HD proposed in this work should also provide a convenient means for testing relevant therapies for HD.